1. Technical Field
The present disclosure relates to a cooling liquid circulation device that circulates cooling liquid for an internal combustion engine.
2. Description of Related Art
A cooling liquid circulation device for an internal combustion engine has cooling liquid passages which are constituted by a water jacket and the like inside the internal combustion engine and through which cooling liquid circulates, an electric pump that force-feeds and circulates the cooling liquid in the cooling liquid passages, and control valves that are provided in the cooling liquid passages to block up the passages (see Published Japanese Translation of PCT Application No. 2013-525653 (JP 2013-525653 A)).
In the device of Published Japanese Translation of PCT Application No. 2013-525653 (JP 2013-525653 A), each of the control valves has a spring that constantly urges a valve body in a valve-closing direction, and an electromagnet that suctions the valve body in the valve-closing direction. This electromagnet has a core and a winding (a coil), and generates a magnetic force for suctioning the valve body in the valve-closing direction through energization of the coil. Besides, the valve body of each of the control valves is structured to be urged in a valve-opening direction by the flow momentum of the cooling liquid passing through the interior of each of the control valves.
A changeover from a state where the valve body of this control valve is unseated (an open-valve state) to a state where the valve body is seated (a closed-valve state) is made as follows. First of all, the operation of the pump is temporarily stopped, and the circulation of cooling liquid is stopped. Thus, the urging force that is applied to the valve body of each of the control valves in the valve-opening direction by the flow momentum of cooling liquid disappears, so the valve body is moved in the valve-closing direction and seated by an urging force of the aforementioned spring. Then, at this moment, the coil of each of the control valves is energized. Thus, the electromagnet of each of the control valves generates a magnetic force, so the valve body is held seated by a suction force resulting from this magnetic force. After that, the operation of the pump is resumed, and the circulation of cooling liquid is resumed. At this moment, although the valve body is urged in the valve-opening direction by the flow momentum of cooling liquid, the suction force of the electromagnet holds the valve body closed.